BUFFON'S SKUA. 637 



Bay, and Spitzbergen. It resembles the Lestris pomarinus 

 in its manners." The egg, as figured by Thienemann, fs 

 of a pale green colour, spotted with ash grey and dark 

 reddish brown ; the measurements are two inches in 

 length, by one inch and five lines in breadth. 



In the adult bird the base of the bill, including the cere, is 

 dark greenish brown, the horny, curved point, black ; irides 

 brown ; all the upper part of the head black ; sides and 

 back of the neck white, tinged with straw yellow ; back, 

 tertials, wing, and tail- coverts brownish -grey ; primaries 

 and tail-feathers almost black ; chin, throat, and upper 

 part of belly white ; lower part of the belly, the vent, and 

 under tail-coverts, light brownish-grey ; legs, toes, and 

 their membranes black : the tarsi still bearing some traces 

 of their previous yellow colour. 



The whole length of the specimen described, from the 

 point of the beak to the end of the tail-feather next the 

 central pair, is thirteen inches and a half, the central fea- 

 thers extending nine inches beyond ; the wing, from the 

 anterior bend to the end of the longest quill-feather, 

 twelve inches ; the tarsus one inch and a half ; the middle 

 toe and the claw rather shorter, or one inch and three- 

 eighths. 



Independently of the difference in measurements, adult 

 birds of this species, compared with old ones of the species 

 previously described, have the head always much darker in 

 colour, while the back is lighter. 



